1. Field of the Invention
The present invention relates to an engine mount having an inner and an outer metal fitting elastically connected by a rubber elastic body, wherein the inner and outer fittings attached to a component on the engine side and a component on the body-side, to reduce engine vibration.
2. Description of the Related Art
Known engine mounts of this kind for use in automotive vehicles include one with a design such as that taught for example in JP-A-10-47402, which comprises a round cylindrical inner member, a cylindrical outer member disposed coaxially with the inner member and spaced outwardly apart therefrom, and a pair of rubber elastic arms extending from both diametrical sides of the inner member to the outer member to elastically connect the two members. By means of the pair of rubber elastic arms, this engine mount attenuates vibration in the vertical, left-right, and front-back directions of the vehicle. The engine mount has a high spring constant in the vertical and left-right directions with respect to the front-back direction of the vehicle (high spring constant in the axis-perpendicular directions with respect to spring constant in the axial direction), for example, a vertical direction (axis-perpendicular direction):left-right direction (axis-perpendicular direction):front-back direction (axial direction) spring constant ratio on the order of 1:0.3:0.2. The engine mount is installed mounted between the vehicle body and the engine with the axial direction facing front-to-back of the vehicle, in order to provide damping of larger vibration in the vehicle vertical direction and left/right direction by spring in the axis-perpendicular direction, and of smaller vibration in the vehicle front/back direction by spring in the axial direction.
In this type of engine mount, for reasons relating to component space in the vehicle or to engine mount installation, the mounting cannot be positioned with the axial direction in the front-back direction of the vehicle, but must instead be positioned facing in the left-right direction. In the event that the engine mount is positioned with the axial direction facing in the left-right direction of the vehicle, there arises problem of inability to adequate attenuate vibration in the left-right direction due to the low spring constant in the axial direction. That is, in the event that the axial direction of the engine mount is positioned facing in the left-right direction of the vehicle, the vertical direction (axis-perpendicular direction):left-right direction (axial direction): front-back direction (axis-perpendicular direction) spring constant ratio will be on the order of 1:0.2:0.3, with the spring constant in the left-right direction being quite low. In a different design such as that taught in JP-U-5-57468, rubber stops is disposed at the axial ends, so that shook in the axial direction is absorbed by the rubber stops in addition to the rubber elastic body. However, it is difficult to install separate rubber stops on the two axial sides, making the engine mount more expensive.